Integrated screw compressor motor

ABSTRACT

A screw compressor is provided and includes a housing (11), helical screws (21, 24) disposed within the housing (11) for rotation about respective rotational axes (RA1, RA2) in a mutually engaged relationship, at least one stator (30, 40) disposed within the housing (11) about a corresponding one of the helical screws (21, 24) and a conductive element (50, 60). The conductive element (50, 60) is wound about the at least one stator (30, 40) such that current applied to the conductive element (50, 60) generates a flux field by which the corresponding one of the helical screws (21, 24) is driven to rotate about the corresponding rotational axis (RA1, RA2).

BACKGROUND OF THE DISCLOSURE

The subject matter disclosed herein relates to compressors and, more particularly, to an integrated screw compressor motor.

Rotary-screw compressors (or screw compressors, for short) typically employ rotary-type positive-displacement mechanisms and are used where large volumes of high-pressure fluid are needed for large industrial applications or to operate high-power tools. Screw compressors usually include two meshing helical screws, known as rotors, to compress a fluid. In a dry-running or oil free screw compressor, timing gears ensure that male and female rotors maintain precise alignment. In an oil-flooded screw compressor, lubricating oil bridges the space between the rotors, both providing a hydraulic seal and transferring mechanical energy between the driving and driven rotor. In any case, fluid enters screw compressors at their suction sides and moves through the threads as the screws rotate. The meshing rotors force the fluid through the compressors and the fluid exits at the end of the screws in a compressed state.

For oil free screw compressors, the male rotor is driven by a motor and a gear is attached at the opposite end. Another gear is attached to female rotor to mesh with the gear on the male rotor. The gear set maintains a clearance between the rotors and drives the female. The presence of the motor and gears and the rotor shaft extensions thus requires that one or more additional housings be added to the screw compressor housing to support and retain the motor and gears and the rotor shaft extensions. This additional housing material increases costs and leads to decreased efficiencies due to windage losses, for example.

BRIEF DESCRIPTION OF THE DISCLOSURE

According to one aspect of the disclosure, a screw compressor is provided and includes a housing, helical screws disposed within the housing for rotation about respective rotational axes in a mutually engaged relationship, at least one stator disposed within the housing about a corresponding one of the helical screws and a conductive element. The conductive element is wound about the at least one stator such that current applied to the conductive element generates a flux field by which the corresponding one of the helical screws is driven to rotate about the corresponding rotational axis.

In accordance with additional or alternative embodiments, the helical screws and the at least one stator are laminated.

In accordance with additional or alternative embodiments, the helical screws respectively include a male helical screw and a female helical screw.

In accordance with additional or alternative embodiments, the male helical screw includes a first hub and multiple protrusions extending outwardly from the first hub in a helical formation along a length of the first hub, the female helical screw includes a second hub and multiple recess-defining protrusions extending outwardly from the second hub in a helical formation along a length of the second hub and the at least one stator includes helical teeth about which the conductive element is wound.

In accordance with additional or alternative embodiments, the conductive element extends about a partial arc-length of a circumference of the corresponding one of the helical screws.

In accordance with additional or alternative embodiments, the screw compressor further includes rotor shafts about which the helical screws are rotatable and bearings coupled to the housing to rotatably support the rotor shafts.

In accordance with additional or alternative embodiments, a controller is configured to control rotations of the helical screws such that the helical screws remain separated during rotations thereof.

In accordance with another aspect of the disclosure, a screw compressor is provided and includes a housing, first and second helical screws disposed within the housing for rotation about first and second rotational axes, respectively, in a mutually engaged relationship, first and second stators disposed within the housing about the first and second helical screws, respectively, and first and second conductive elements. The first and second conductive elements are wound about the first and second stators, respectively, such that current applied to the first and second conductive elements generates flux fields by which the first and second helical screws are driven to rotate about the first and second rotational axes, respectively.

In accordance with additional or alternative embodiments, the first and second helical screws and the first and second stators are laminated.

In accordance with additional or alternative embodiments, the first and second helical screws respectively include a male helical screw and one or more female helical screws. The male helical screw includes a first hub and multiple protrusions extending outwardly from the first hub in a helical formation along a length of the first hub and each of the one or more female helical screws includes a second hub and multiple recess-defining protrusions extending outwardly from the second hub in a helical formation along a length of the second hub.

In accordance with additional or alternative embodiments, the first and second stators include helical teeth about which the first and second conductive elements are wound.

In accordance with additional or alternative embodiments, the first conductive element extends about a partial arc-length of a circumference of the first helical screw and the second conductive element extends about a partial arc-length of a circumference of the second helical screw.

In accordance with additional or alternative embodiments, the screw compressor further includes a first rotor shaft about which the first helical screw is rotatable, first bearings coupled to the housing to rotatably support the first rotor shaft, a second rotor shaft about which the second helical screw is rotatable and second bearings coupled to the housing to rotatably support the second rotor shaft.

In accordance with additional or alternative embodiments, a controller is configured to control rotations of the first and second helical screws such that the first and second helical screws remain separated during rotations thereof.

In accordance with yet another aspect of the disclosure, a fluid system is provided. The fluid system includes an inlet, an outlet and a screw compressor fluidly interposed between the inlet and the outlet. The screw compressor includes a housing which is receptive of fluid from the inlet and which is configured to direct the fluid into the outlet, first and second helical screws disposed within the housing for rotation about first and second rotational axes, respectively, in a mutually engaged relationship to compress the fluid received from the inlet and directed into the outlet, first and second stators disposed within the housing about the first and second helical screws, respectively, and first and second conductive elements. The first and second conductive elements are wound about the first and second stators, respectively, such that current applied to the first and second conductive elements generates flux fields by which the first and second helical screws are driven to rotate about the first and second rotational axes, respectively.

In accordance with additional or alternative embodiments, the first and second helical screws and the first and second stators are laminated.

In accordance with additional or alternative embodiments, the first and second helical screws respectively include a male helical screw and one or more female helical screws. The male helical screw includes a first hub and multiple protrusions extending outwardly from the first hub in a helical formation along a length of the first hub and each of the one or more female helical screw includes a second hub and multiple recess-defining protrusions extending outwardly from the second hub in a helical formation along a length of the second hub.

In accordance with additional or alternative embodiments, the first and second stators include helical teeth about which the first and second conductive elements are wound.

In accordance with additional or alternative embodiments, the first conductive element extends about a partial arc-length of a circumference of the first helical screw and the second conductive element extends about a partial arc-length of a circumference of the second helical screw.

In accordance with additional or alternative embodiments, the screw compressor further includes a first rotor shaft about which the first helical screw is rotatable, first bearings coupled to the housing to rotatably support the first rotor shaft, a second rotor shaft about which the second helical screw is rotatable and second bearings coupled to the housing to rotatably support the second rotor shaft.

In accordance with additional or alternative embodiments, a controller is configured to control rotations of the first and second helical screws such that the first and second helical screws remain separated during rotations thereof.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

The subject matter, which is regarded as the disclosure, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side view of a fluid system in accordance with embodiments;

FIG. 2 is a side view of a screw compressor of the fluid system of FIG. 1 in accordance with embodiments;

FIG. 3 is an axial view of the screw compressor of FIG. 2;

FIG. 4 is a side view of helical screws of the screw compressor of FIG. 2;

FIG. 5 is a schematic axial view of a first stator of the screw compressor of FIG. 2;

FIG. 6 is a schematic axial view of a second stator of the screw compressor of FIG. 2;

FIG. 7 is a schematic diagram illustrating a power circuit by which the screw compressor is operated in accordance with embodiments; and

FIG. 8 is a schematic diagram illustrating a power circuit by which the screw compressor is operated in accordance with embodiments.

The detailed description explains embodiments of the disclosure, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE DISCLOSURE

As will be described below, an oil-free screw compressor is provided within a compressor housing with a motor stator and windings that are integrated within the housing. The screw compressor thus has a compact size and operates at an increased efficiency owing to reduced windage losses.

With reference to FIG. 1, a fluid system 10 is provided. The fluid system 10 includes a screw compressor housing 11, an inlet 12 and an outlet 13. The screw compressor housing 11 houses a screw compressor 20 with a motor stator and windings (all to be described in detail below) that are integrated within the compressor housing 11. The screw compressor housing 11 has a first opening at a first end thereof whereby the compressor housing 11 is fluidly coupled with the inlet 12 to be receptive of fluid from the inlet 12 and a second opening at a second end thereof whereby the compressor housing 11 is fluidly coupled with the outlet 13 such that the compressor housing 11 can direct fluid into the outlet 13. The compressor housing 11, the inlet 12 and the outlet 13 are each configured to define respective interiors such that the fluid system 10 is formed to define a fluid pathway 14 extending from the inlet 12, through the compressor housing 11 and into the outlet 13.

Although the inlet 12 and the outlet 13 are illustrated as being radially oriented relative to the compressor housing 11, it is to be understood that this is not required. For example, one or both of the inlet 12 and the outlet 13 may be axially oriented relative to the compressor housing 11 instead.

With reference to FIG. 2, the screw compressor 20 is housed almost entirely within the compressor housing 11. The screw compressor 20 includes a first helical screw 21, a first rotor shaft 22 and first bearings 23. The first bearings 23 rotatably support the first rotor shaft 22 at end walls of the compressor housing 11. The first helical screw 21 is formed of multiple laminations that are laminated together and disposed as a unit on the first rotor shaft 22 to rotate with the first rotor shaft 22 about a first rotational axis RA1. The screw compressor 20 further includes a second helical screw 24, a second rotor shaft 25 and second bearings 26. The second bearings 26 rotatably support the second rotor shaft 25 at the end walls of the compressor housing 11. The second helical screw 24 is formed of multiple laminations that are laminated together and disposed as a unit on the second rotor shaft 25 to rotate with the second rotor shaft 25 about a second rotational axis RA2.

The first and second helical screws 21 and 24 are disposed within the compressor housing 11 for rotation about the first and second rotational axes RA1 and RA2, respectively, in a mutually engaged relationship to compress the fluid received by the compressor housing 11 from the inlet 12 and directed into the outlet 13.

The screw compressor 20 also includes a first stator 30, which is integrated into the compressor housing 11, a second stator 40, which is integrated into the compressor housing 11, a first conductive element 50 and a second conductive element 60. The first conductive element 50 may be provided as insulated steel laminations with insulated metallic wire (e.g., a copper wire with insulation surrounding the copper in each winding) with windings and end turns. The windings and end turns are wound about the first stator 30 within the compressor housing 11. Similarly, the second conductive element 60 may be provided as insulated steel laminations with insulated metallic wire (e.g., a copper wire with insulation surrounding the copper in each winding) with windings and end turns. The windings and end turns are wound about the second stator 40 within the compressor housing 11. As such, current applied to the first and second conductive elements 50 and 60 generates flux fields by which the first and second helical screws 21 and 24 are driven to rotate about the first and second rotational axes RA1 and RA2, respectively.

Since the rotations of the first and second helical screws 21 and 24 are driven by the generated flux fields as described above, the fluid system 10 as a whole can be operated in an oil-free condition.

Although FIG. 2 illustrates that the screw compressor 20 includes the first and second stators 30 and 40 and the first and second conductive elements 50 and 60, it is to be understood that this is not necessary and that other configurations are possible. For example, the screw compressor 20 may only include the first stator 30 and the first conductive element 50 in which case the first helical screw 21 is driven to rotate about the first rotational axis RA1 and the second helical screw 24 acts a dummy or passive screw. As another example, the screw compressor 20 may only include the second stator 40 and the second conductive element 60 in which case the second helical screw 24 is driven to rotate about the second rotational axis RA2 and the first helical screw 21 acts a dummy or passive screw. For purposes of clarity and brevity, however, the following description will relate to the case of the screw compressor 20 including the first and second stators 30 and 40 and the first and second conductive elements 50 and 60.

With reference to FIGS. 3 and 4, the first helical screw 21 includes or is provided as a male helical screw 210 and the second helical screw 24 includes or is provided as one or more female helical screws 240. As shown in FIG. 3, the male helical screw 210 includes a first hub 211 and multiple protrusions 212 that extend outwardly from the first hub 211 while each of the one or more female helical screws 240 includes a second hub 241 and multiple recess-defining protrusions 242 that extend outwardly from the second hub 241. As shown in FIG. 4, these multiple protrusions 212 extend outwardly in a first helical formation 213 along a longitudinal length of the first hub 211 while the multiple recess-defining protrusions 242 extend outwardly in a second helical formation 243 along a longitudinal length of the second hub 241.

For purposes of clarity and brevity, the following description will relate to only the case of a single female helical screw 240 being provided with a single male helical screw 210.

At each axial location of the first and second helical screws 21 and 24, at least one of the multiple protrusions 212 is received within and thus engages with at least a corresponding one of the multiple recess-defining protrusions 242 to compress fluid ingested between the first and second helical screws 21 and 24 at a given moment. The first and second helical formations 213 and 243 tend to drive the fluid being compressed in an axial direction (e.g., from the inlet 12 and the first end of the compressor housing 11 to the second end of the compressor housing 11 and into the outlet 13).

With reference to FIGS. 5 and 6, the first and second stators 30 and 40 each include first and second helical teeth 31 and 41 about which the first and second conductive elements 50 and 60 are wound, respectively. As shown in the solid, dashed and dotted lines representing the first and second helical teeth 31 and 41 in FIGS. 5 and 6, the first and second helical teeth 31 and 41 skew in their respective angular or circumferential position along an axial length of the first and second hubs 211 and 241. The skews for each of the first and second teeth 31 and 42 are each defined in accordance with the respective helical pitches of the helical formations 213 and 243 such that the first and second stators 30 and 40 and the first and second conductive elements 50 and 60 remain in phase with the first and second helical screws 21 and 24. With this configuration, the first and second helical screws 21 and 24 (whose multiple protrusions 212 and multiple recess-defining protrusions 242 are shaped like salient poles) effectively function as switch reluctance type motors when current is applied to the first and second conductive elements 50 and 60.

With reference to back to FIG. 3 and with continued reference to FIGS. 5 and 6, the first conductive element 50 is wound about the first teeth 31 of the first stator 40 such that the first conductive element 50 extends about a partial arc-length of a circumference of the first helical screw 21 and the second conductive element 60 is wound about the second teeth 41 of the second stator 40 such that the second conductive element 60 extends about a partial arc-length of a circumference of the second helical screw 24. The partial arc-lengths may be about 260-270 degrees about the first and second helical screws 21 and 24, respectively, although they are drawn in FIGS. 3, 5 and 6 as being slightly greater than 180 degrees for clarity.

With reference to FIGS. 7 and 8, the fluid system 10 may further include a power source 70, such as a battery, that is electrically coupled with both the first and second conductive elements 50 and 60 (see FIG. 7) or with only one of the first and second conductive elements 50 and 60 (see FIG. 8 in which the power source 70 is coupled with only the first conductive element 50).

In the case of FIG. 7 where the first and second conductive elements 50 and 60 are coupled with the power source 70, the first and second helical screws 21 and 24 are driven to rotate about the first and second rotational axes RA1 and RA2, respectively. Here, the relative amounts of current applied to the first and second conductive elements 50 and 60 may be substantially similar or biased toward one of the first and second conductive elements 50 and 60. That is, in accordance with embodiments, the first conductive element 50 may be supplied with an amount of current that is 8-10 or more times the magnitude of the amount of current supplied to the second conductive element 60 (i.e., the torque applied to the first helical screw 21 exceeds the torque applied to the second helical screw 24 by 8-10 or more times).

By contrast, in the case of FIG. 8, where only the first conductive element 50 is coupled with the power source 70, only the first helical screw 21 is driven to rotate about the first rotational axis RA1 while the second helical screw 24 rotates about the second rotational axis RA2 as a dummy or passive screw. Here, the available current is entirely applied to the first conductive element 50.

As an additional feature, as shown in FIGS. 7 and 8, the fluid system 10 may include a controller 80 that is provided to control various operations of the power source 70 and the first and/or second conductive elements 50 and 60. For example, the controller 80 may operate the fluid system 10 such that the respective active or passive rotations of the first and second helical screws 21 and 24 about the first and second rotational axes RA1 and RA2 and executed independently of one another or dependent upon one another.

As such, with additional reference back to FIGS. 1 and 2, the controller 80 may include a sensor array having multiple pressure sensors 81 and 82 and multiple angular, positional sensors 83. The pressure sensors 81 and 82 are operably disposed within at least one or both of the inlet 12 and the outlet 13, respectively. The angular, positional sensors 83 are operably disposed about or on the first and second helical screws 21 and 24 to monitor fluid pressures and rotational speeds and angular positions thereof. Using feedback control, for example, the controller 80 can be receptive of angular, positional readings of the first and second helical screws 21 and 24 from the angular, positional sensors 83 and increase or decrease the rotational speeds of the first and second helical screws 21 and 24 accordingly. In so doing, the controller 80 can insure that the first and second helical screws 21 and 24 remain separated and out of contact with one another.

While the disclosure is provided in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that the exemplary embodiment(s) may include only some of the described exemplary aspects. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims. 

What is claimed is:
 1. A screw compressor, comprising: a housing; helical screws disposed within the housing for rotation about respective rotational axes in a mutually engaged relationship; at least one stator disposed within the housing about a corresponding one of the helical screws; and a conductive element wound about the at least one stator such that current applied to the conductive element generates a flux field by which the corresponding one of the helical screws is driven to rotate about the corresponding rotational axis.
 2. The screw compressor according to claim 1, wherein the helical screws and the at least one stator are laminated.
 3. The screw compressor according to claim 1, wherein the helical screws respectively comprise a male helical screw and a female helical screw, wherein: the male helical screw comprises a first hub and multiple protrusions extending outwardly from the first hub in a helical formation along a length of the first hub, the female helical screw comprises a second hub and multiple recess-defining protrusions extending outwardly from the second hub in a helical formation along a length of the second hub, and the at least one stator comprises helical teeth about which the conductive element is wound.
 4. The screw compressor according to claim 1, wherein the conductive element extends about a partial arc-length of a circumference of the corresponding one of the helical screws.
 5. The screw compressor according to claim 1, further comprising: rotor shafts about which the helical screws are rotatable; and bearings coupled to the housing to rotatably support the rotor shafts.
 6. The screw compressor according to claim 1, further comprising a controller configured to control rotations of the helical screws such that the helical screws remain separated during rotations thereof.
 7. A screw compressor, comprising: a housing; first and second helical screws disposed within the housing for rotation about first and second rotational axes, respectively, in a mutually engaged relationship; first and second stators disposed within the housing about the first and second helical screws, respectively; and first and second conductive elements wound about the first and second stators, respectively, such that current applied to the first and second conductive elements generates flux fields by which the first and second helical screws are driven to rotate about the first and second rotational axes, respectively.
 8. The screw compressor according to claim 7, wherein the first and second helical screws and the first and second stators are laminated.
 9. The screw compressor according to claim 7, wherein the first and second helical screws respectively comprise a male helical screw and one or more female helical screw, wherein: the male helical screw comprises a first hub and multiple protrusions extending outwardly from the first hub in a helical formation along a length of the first hub, and each of the one or more female helical screws comprises a second hub and multiple recess-defining protrusions extending outwardly from the second hub in a helical formation along a length of the second hub.
 10. The screw compressor according to claim 7, wherein the first and second stators comprise helical teeth about which the first and second conductive elements are wound.
 11. The screw compressor according to claim 7, wherein: the first conductive element extends about a partial arc-length of a circumference of the first helical screw, and the second conductive element extends about a partial arc-length of a circumference of the second helical screw.
 12. The screw compressor according to claim 7, further comprising: a first rotor shaft about which the first helical screw is rotatable; first bearings coupled to the housing to rotatably support the first rotor shaft; a second rotor shaft about which the second helical screw is rotatable; and second bearings coupled to the housing to rotatably support the second rotor shaft.
 13. The screw compressor according to claim 7, further comprising a controller configured to control rotations of the first and second helical screws such that the first and second helical screws remain separated during rotations thereof.
 14. A fluid system, comprising: an inlet; an outlet; and a screw compressor fluidly interposed between the inlet and the outlet and comprising: a housing which is receptive of fluid from the inlet and which is configured to direct the fluid into the outlet; first and second helical screws disposed within the housing for rotation about first and second rotational axes, respectively, in a mutually engaged relationship to compress the fluid received from the inlet and directed into the outlet; first and second stators disposed within the housing about the first and second helical screws, respectively; and first and second conductive elements wound about the first and second stators, respectively, such that current applied to the first and second conductive elements generates flux fields by which the first and second helical screws are driven to rotate about the first and second rotational axes, respectively.
 15. The fluid system according to claim 14, wherein the first and second helical screws and the first and second stators are laminated.
 16. The fluid system according to claim 14, wherein the first and second helical screws respectively comprise a male helical screw and one or more female helical screws, wherein: the male helical screw comprises a first hub and multiple protrusions extending outwardly from the first hub in a helical formation along a length of the first hub, and each of the one or more female helical screws comprises a second hub and multiple recess-defining protrusions extending outwardly from the second hub in a helical formation along a length of the second hub.
 17. The fluid system according to claim 14, wherein the first and second stators comprise helical teeth about which the first and second conductive elements are wound.
 18. The fluid system according to claim 14, wherein: the first conductive element extends about a partial arc-length of a circumference of the first helical screw, and the second conductive element extends about a partial arc-length of a circumference of the second helical screw.
 19. The fluid system according to claim 14, further comprising: a first rotor shaft about which the first helical screw is rotatable; first bearings coupled to the housing to rotatably support the first rotor shaft; a second rotor shaft about which the second helical screw is rotatable; and second bearings coupled to the housing to rotatably support the second rotor shaft
 20. The fluid system according to claim 14, further comprising a controller configured to control rotations of the first and second helical screws such that the first and second helical screws remain separated during rotations thereof. 